1. Field of the Invention
This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to a method for synthesizing a silicon (Si) nanoparticle solution suitable for deposition of Si nanoparticles.
2. Description of the Related Art
The electrochemical etching of Si wafers in an electrolyte containing hydrofluoric acid, methanol, and some catalysts can generate nano/micro structures on the wafer surface. The porous Si surface is then pulverized in an ultrasonication bath to produce Si nanoparticles, as reported in J. Am. Chem. Soc., 129, pp. 5326-5327, 2007. Without oxidation or other surface passivation, the as-synthesized Si nanoparticles should be hydrogen-terminated, which makes the particles not soluble in several organic solvents that are commonly used for spin-coating, drop-casting or inkject printing. Currently, the Si nanoparticles synthesized from solution-based precursor reduction methods demonstrate versatile surface chemistry due to their chemically active surface termination (e.g., chloride, bromide, and hydride) that allows for subsequent derivatization. However, no solution-based chemical method has been found for cost-effective industrial production owing to the need for a critical synthesis condition, special equipment, and complex purification procedures.
It would be advantageous if there was an electrochemical etching method, which only required commercially available Si wafers, common electrolytes, and performance in an ambient condition, that could be used to synthesize Si nanoparticles directly from bulk Si wafers (n- or p-type), for low-cost, large-quantity and high-throughput applications.